1. Field of the Invention
The present invention relates to an antibody or a monoclonal antibody used for specifically measuring active hepatocyte growth factor activator (HGFA), a method for using the same and a measurement kit. The present invention also relates to a method for detecting a disease of patient in a pathological condition, in particular, organ inflammation, glomerular nephritis, cancer, myocardial infarction, angina pectoris or thrombosis, by using the active HGFA as an index and further relates to a method for collecting a biological component and blood, which is suitable for performing the method.
2. Description of the Related Art
Protease (protein decomposition enzyme) is a protein having a function of hydrolyzing a peptide bond in a protein or a peptide and it is deeply involved in organic functions and, at the same time, plays an important role in maintenance of homeostasis thereof. For example, various proteases existing in blood themselves constitute dense cascades and control coagulation and fibrinolysis of blood.
A hepatocyte growth factor activator (hereinafter abbreviated as “HGFA”) is known as a kind of serine protease having a serine residue in its active center (Miyazawa et al., J. Biol. Chem., 268, pp.10024–10028, 1993). Unlike common proteases in blood involved in the blood coagulation/fibrinolysis system cascades, HGFA has a unique characteristic of acting on a hepatocyte growth factor (hereinafter abbreviated as “HGF”), which is known as a cytokine involved in hepatocyte growth or organ regeneration (Naka et al., J. Biol. Chem., 267, pp.20114–20119, 1992), to specifically and limitedly decompose it and thereby activate it (Shimomura et al., Cytotechnology, 8, pp.219–229 (1992)). However, as for the action of HGFA, only the activation of HGF is known in animal model experiments using rats or in vitro experiments (Miyazawa et al., J. Biol. Chem., 271, pp.3615–3618, 1996), and its roles and functions in human pathologic conditions and the relationship of its blood level and pathologic conditions have not been known at all.
As HGFA, there are known one showing a molecular weight of about 96,000–98,000 determined by SDS-PAGE (hereafter, abbreviated as “98 kDa HGFA”) and one showing a molecular weight of about 34,000–38,000 (hereafter, abbreviated as “36 kDa HGFA”), which is a peptide on the C terminus side of the protein provided by limited proteolysis at a bond between arginine at a position of 372 and the valine at a position of 373, which are counted from the translation initiation amino acid. The variation in the molecular weights is caused by heterogeneity in the bonding amount of sugar chains and differences in measured molecular weight values attributable to whether the measurement by the SDS-PAGE method was performed under reducing or non-reducing condition, and these are essentially the same protein. Further, each HGFA usually exists as an inactive substance in blood, but is activated by limited proteolysis at a bond between the arginine at position of 407 and isoleucine at a position of 408, which are counted from the translation initiation amino acid, and thus single chain HGFA is converted to double chain HGFA, which is heterodimerized with a disulfide bond. This activated HGFA is considered to specifically activate the substrate, HGF (Shimomura et al., J. Biol. Chem., 268, pp.22927–22932, 1993).
To analyze the relationship between the HGFA blood level and pathological conditions, active HGFA existing in biological component such as human tissues, humors or blood needs to be specifically measured. Further, to specifically detect or measure active HGFA, it is essential to obtain an antibody, particularly preferably a monoclonal antibody, that recognizes active HGFA extremely specifically, but does not substantially recognize inactive HGFA. However, any antibody having such a characteristic has not known at all so far. Further, there is no method or kit specifically used for measuring active HGFA existing in a biological component such as human blood.